The present disclosure relates to subject matter contained in Japanese Patent Application No. 7-199650 (filed on Aug. 4, 1995) and Japanese Patent Application No. 7-257328 (filed on Oct. 4, 1995), which are expressly incorporated herein by reference in their entireties.
1. Field of the Invention
The present invention relates to a portable endoscope having an illuminating light supply unit which contains a light source lamp for supplying illuminating light to a light guide.
2. Description of the Prior Art
A conventional portable endoscope has a light-emitting device for illumination which is provided in an endoscope control part. In general, such a portable endoscope has an illuminating light supply unit which contains a light source lamp and a power supply for the lamp, e.g. a dry battery, and the illuminating light supply unit is detachably connected to the control part. ON/OFF control of the light source lamp is effected using a manual switch which is provided on the illuminating light supply unit.
However, in a case where the light source lamp is turned ON/OFF with a manual switch provided on the illuminating light supply unit, the light source lamp may be left in the ON state when it is not needed, causing battery power to be wasted.
Particularly, if the operator forgets to turn OFF the switch when the illuminating light supply unit is detached from the endoscope control part after the use of the endoscope, there are cases where the battery has run down before the operator realizes it, and hence, the light source lamp cannot be lit up when the endoscope is used for a subsequent endoscopic inspection (endoscopy).
In addition, the illuminating light supply unit that is connected directly to the control part of the endoscope must be arranged to be as compact and lightweight as possible in order to prevent the illuminating light supply unit from impairing the controllability of the endoscope.
The switch that is used to turn ON/OFF the light source lamp is a switch which merely performs ON/OFF control. Therefore, it is likely that the light source lamp will be burned out by an inrush current that flows when the switch is turned ON to light the light source lamp.
Particularly, when a rechargeable secondary battery is used as a power supply, the power supply voltage may exceed the rated value immediately after the battery has been charged. When an AC/DC adapter is used as a power supply, a voltage drop is less likely to occur when the power is turned ON than in the case of a battery. Therefore, in these cases, the light source lamp is likely to be burned out by an inrush current.